1. Technical Field
The present disclosure relates to surface treating methods and, particularly, to a method for surface treating a cold cathode.
2. Description of Related Art
The cold cathode prepared by a screen-printing method is low cost and can be used for field emission flat-panel displays and other vacuum microelectronic devices. Conventional cold cathodes can be prepared by screen-printing a mixture of carbon nanotubes and ordinary conductive paste or a mixture of carbon nanotubes, conductive silver powders, binding materials, and an organic solvent. After a high temperature treatment, the organic solvent is removed, and the acquired cold cathode can include carbon nanotubes, conductive metal particles, and glass-phase solid binding materials. The carbon nanotubes can be located at a surface of the cold cathode and serve as emitters thereof.
However, the surface of the cold cathode is always covered by glass-phase solid binding materials and other impurities, and the number of the carbon nanotubes exposed out of the surface thereof is low, thus the emitting current of the cold cathode is low. Therefore, it is necessary to use a surface treating method to improve the emitting properties of the cold cathode.
A conventional method for treating the cold cathode is executed using a sticky tape. The sticky tape is adhered on a surface of the cold cathode, heated to a certain temperature, and then taken away from the cold cathode to cause the carbon nanotubes at the surface of the cold cathode to stand erect. However, a heating temperature of the sticky tape affects the cold cathode. If the heating temperature is too low, the carbon nanotubes would be completely removed from the surface of the cold cathode. If the heating temperature is too high, there would be sticky tape residue on the surface of the cold cathode, thereby affecting emission properties and lifetime of the cold cathode. Further, when the sticky tape is adhered on the surface of the cold cathode, it is difficult for the sticky tape to closely contact the surface of the cold cathode, resulting in air filled between the sticky tape and the cold cathode. The carbon nanotubes exposed to the air will not contact the sticky tape. Accordingly, when the sticky tape is taken away from the cold cathode, the carbon nanotubes exposed to the residual air are arranged disorderly, thereby reducing field emission uniformity of the cold cathode.
What is needed, therefore, is a method for surface treating a cold cathode in which the above problems are eliminated or at least alleviated.